CAYKARA, Turkey — Their collars pulled up against the evening cold, a group of men and women peer through binoculars, scanning the fields along a barbed wire fence. A few kilometers (miles) away across the Turkish border, black smoke rises from the besieged Kurdish Syrian town of Kobani, the dull thud of mortars carrying across on the breeze.

They are some of the hundreds of volunteers, predominantly Kurdish Turks, who have traveled from villages, towns and cities across southeastern Turkey and even from Istanbul, to keep watch on the border. They are on the lookout for potential fighters of the extremist Islamic State group attempting to cross into Kobani, besieged since mid-September by IS and defended by Kurdish Syrian fighters known as the People's Protection Units.

"To be honest, we don't trust (the Turkish border guards), because we have seen many occasions that the Turkish government has loosened its borders for ISIS fighters, weapons and logistical support to cross," said Ibrahim Binici, a Kurdish lawmaker for the left-wing HDP party, which put out a call in September for the volunteers.

It's a claim Turkey vehemently rejects. But the deep distrust of Turkish authorities in the border area reflects Turkey's complicated attitude toward the Islamic extremists who captured swaths of Iraq and Syria, and its strained relations with its own Kurdish population.

The country's reluctance to join a U.S.-led international coalition action against IS in Syria and Iraq, mainly through airstrikes, has frustrated Turkey's American and European allies. Ankara, however, insists the priority should be the unseating of Syrian President Bashar al-Assad, whose 2011 crackdown on protesters sparked an uprising that soon spun into a vicious civil war.

Turkey's position on IS is "ambivalent at best, uncertain at worse," said Serhat Guvenc, international relations professor at Istanbul's Kadir Has University.

One reason, Guvenc explained, is that Turkey suspects IS "is here to stay" — that the group will eventually become part of the Sunni establishment in Syria and Iraq, which also borders Turkey. Ankara therefore fears it will inevitably have to deal with the group.

Another is the Kurdish issue. Separatists, mainly led by the Kurdistan Workers Party, or PKK, have fought a 30-year guerrilla war in Turkey's southeast which has left tens of thousands dead. An uneasy ceasefire has been in place for only about two years. The PKK is on the terrorist list of Turkey, the European Union and the U.S., and Ankara is deeply suspicious of the People's Protection Units, which it views as an extension of the PKK.

When the IS onslaught in Kobani began, Turkish Kurds were furious that their government was not doing more against IS or allowing them to cross into Syria to help fellow Kurds defend the town from extremists beheading prisoners and carrying out mass executions. Riots in predominantly Kurdish towns and cities ensued, leaving more than a dozen people dead.

But Kurdish resistance in Kobani has been a major public relations success for the Kurds, who have managed — along with the coalition airstrikes — to prevent IS from taking the town.

"Empowerment of the Kurds in the region is kind of upsetting the Turkish positions ... because they're getting credit as the only group in the region that could put up a fight and win against ISIS," said Guvenc.

However, he noted, credit was due to Ankara for recently allowing 150 Peshmerga troops — Kurdish fighters from northern Iraq — to cross through Turkey to bolster the People's Protection Units with artillery in Kobani.

Binici, the Kurdish member of parliament, said the border observers' main aim was to prevent "the mass passage of IS fighters, since you cannot control individuals. ... We believe that we managed to stop that."

About 10,000 people responded to the initial call for volunteers and were deployed in 10 villages. Now, about 2,000-3,000 people remain in three villages, numbers falling due to winter weather and what activists said was targeting by Turkish authorities with tear gas and rubber bullets.

"We've had police intervening and we had many injuries" from the tear gas," said Ipek Gunes, a volunteer from the city of Mardin.

In the villages still hosting volunteers, tents stand among mud and concrete brick houses and meals are provided in outdoor communal kitchens, with everyone taking turns to cook stews in vats over wood fires.

With a roughly 900-kilometer border with Syria and 330-kilometer border with Iraq, Turkey's attraction as an entry point for fighters is obvious. Ankara insists it has cracked down. Checks have increased at ports and airports, a government official said, with 2,000 people interrogated, 1,400 deported and more than 7,000 people denied entry into Turkey since October 2013.

The official, who was not authorized to comment on the issue and therefore demanded anonymity, said allegations of cooperation between border guards and IS fighters were "deliberate disinformation." The army had strengthened border security with fences, thermal cameras and patrols, the official said — but added that authorities "can't check every meter" of the border. The official also noted that hundreds of wounded fighters from the People's Protection Units had been treated in Turkish hospitals.

The foreign ministry did not respond to a request for comment.

The credibility of reports that Turkish guards are ignoring IS fighters crossing the border — or even helping them — is hotly contested. Fighters of the People's Protection Units also cross the border, often using smuggling routes.

"What we are witnessing is part reality, partly constructed reality. There is a big PR war going on, on both sides," said Guvenc. "It seems that the Kurds are more successful at this level of struggle."